Ceramic structured packings are honeycombed structures which are formed by an extruding or injecting method. The packings have a plurality of passages extending there through. The typical unit cross section of the passages has a shape of a regular square, a regular triangle, a hexagon, or the like. Such structures have been found to have a directional quality in mechanical strength.
Traditional structured packing generally have square flow passages (with an aspect ratio equal to one) or circular flow passages or rectangular flow passages or triangular flow passages. Details of such traditional structured packing are available from the websites of manufacturers such as lantecp.com, rauschert.com, ceram.fraunthel.com, and others.
Ceramic structured packings are well described in prior art patents such as U.S. Pat. No. 4,233,351 to Okumura, et al. They are generally manufactured as elongated ceramic blocks having a square cross-section with through longitudinal flow passages for the flow of gas there-through. Generally the blocks are about 2 inches by 2 inches to 6 inches by 6 inches in cross-section and about 2 to 12 inches in length. The dimensions of the blocks are limited by the thermal stress which the “green” (non-fired clay) blocks experience when they are fired to be converted to a ceramic state. The thermal stress may cause some of the blocks to break thereby reducing the product yield of the manufacturing process. Some of the blocks may also break when subjected to the high thermal stress in Regenerative Heat Exchangers. The problems due to thermal stress are described in Okumara et al.
To increase the product yield, special compounds such as Aluminum Oxide are added to the clay to reduce the thermal stress during the firing stage of the process. However, the special compounds add greatly to the cost of the final product. There is therefore a need for a process for making less expensive ceramic structured packing from ordinary clay.
Described herein is a process for making a ceramic structured packing from ordinary clay or less expensive ceramic composites without the use of expensive compounds to reduce thermal stress. The ceramic structured packing described herein has better resistance to thermal stress. Thereby manufacturing yield is increased and breakage during use is also reduced.
The process provides an improved ceramic structured packing which has an excellent mechanical strength and thermal shock resistance. The improved ceramic structured packing is suitable for use in a catalyst carrier for purifying exhaust gases, or as a heat storage media in a regenerative heat exchanger or as a filter for removing particulate matter from a hot gas.
Other advantages of the improved ceramic structured packing will become apparent from the following description of embodiments with reference to the accompanying drawings herein.